Portable Antenna with Built-In Amplifier for Two-Way or One-Way Communications

ABSTRACT

Disclosed are embodiments of portable antennae and systems for radio communications requiring low-noise receiving means, or in which interconnecting transmission line insertion loss between receiver or transceiver equipment and a distant antenna impairs such radio communications. A method of use is also disclosed, in which an antenna in a passive state may be turned on automatically upon the initiation by a radio operator of a transmission.

CROSS-REFERENCES TO RELATED APPLICATIONS

This Divisional application claims the benefit of U.S. Non-Provisionalapplication Ser. No. 15/162,601 filed 23 May 2016. The entire disclosureof the latter patent application is incorporated herein.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

Not applicable.

MICROFICHE APPENDIX

Not applicable.

BACKGROUND OF THE INVENTION 1. Field of the Invention

At least some embodiments disclosed herein relate, in general, to thefield of antennae, radio communication systems, and methods for theiruse, including, but not limited to, those for portable radiocommunications requiring low-noise receiving means and those in whichinterconnecting transmission line insertion loss between receiver ortransceiver equipment and a distant antenna impairs such radiocommunications.

2. Background

The following background information is intended solely for illustrativepurposes, and in no way should be construed as a limitation on theteachings or any embodiments disclosed herein.

The UHF Satcom System is a military communications system utilizing amultiplicity of geosynchronous satellites with dedicated transponders,operating worldwide, 24-hours a day, with operating frequencies from 243MHz to 380 MHz. Currently, various types of satellites comprise thespace-borne network: legacy satellites such as MILSAT, FLTSATCOM,LEASAT, etc., current generation satellites such as Ultra High FrequencyFollow-On (UFO), and new generation satellites, such as the Mobile UserObjective System (MUOS) which first began to be deployed in 2014. Thesesatellites enable communication throughout military assets worldwide;however, during high traffic times, downlink signals from legacy and UFOsatellites become very weak and difficult to receive without the use ofdirectional, high-gain antennas. Although the uplink signal is seldomthe weak link, and an operator in the field may be heard clearly, thedownload signal often proves insufficient to provide the operator withthe ability to receive a clear response consistently and reliably.

A dismounted warfighter (i.e., a combat personnel soldier), which may bein Special Operations Forces (SOF), is considered to be “on foot,” andpossibly engaged in a mission, in which the use of high-gain,directional antennae can be cumbersome and time-consuming, and canseriously compromise the safety of a dismounted warfighter or his teamor unit. High-gain directional antennae currently in use by SOF, whichtypically fold into a relatively small pouch for transport, can berelatively large when deployed for use, and the time required to deployand collapse these antennae are on the order of one to 15 minutes ormore, depending on the gain of the given antenna. Battery-operatedportable radio transceivers carried by military personnel often do nothave sufficient gain or sensitivity to enable UHF Satcom communications,typically used by dismounted warfighters, using a low-gain antenna.These limitations often result in signals that are too weak to beintelligible when they are most needed.

Another limitation with respect to a high-gain antenna is its radiatedfield, which is significantly directional in nature. This requires thatit be pointed towards a satellite to achieve a maximum signal, and thatthis orientation be maintained throughout communications, severelylimiting the mobility of a dismounted warfighter serving as a radiooperator and his SOF team. Furthermore, maximization of high-gainantennae to overcome link budget shortcomings carries with it a risk ofexposing an SOF team to enemy surveillance and direction-findingactivities.

Teams engaged in urban military combat or law enforcement often utilizeportable radio transceivers and an earpiece and microphone combinationfor intra-team coordination and communications. Typically, suchcommunications occur in the VHF or UHF radio spectrum, to limit theeffect of attenuation through structures—walls, floors, etc.—whichincreases with increasing frequency, while keeping antenna size smallenough for effective operation (as antenna size grows when frequency islowered). Urban environments can be challenging for a radio connectiondue to their severe absorption and reflection by large structures, suchas walls and metal structures larger than ½ wavelength at any one ormore dimension, multipath, etc. Furthermore, battery-operatedtransceivers will typically have a low-power output, usually between 100mW and five watts. Long-term health hazards would also limit theradiated power to under five watts. Oftentimes, portable radios aredesigned for cost and enjoy limited sensitivity, which further compoundsto the challenging urban communications environment.

When maintaining communications in frigid or other human hazardousenvironments in the field (outdoors), or in safety and survivalsituations, it is often necessary to place an antenna used to effectcommunications outside a safe area, or at a distance from shelter. Thedistance between an antenna and receiver or transceiver equipment needsto be closed with a transmission line (for example, a coaxial cable),resulting in insertion loss, which is a function of the length of theline, and frequency. The purpose of communications may be to send anemergency signal and be able to receive rescue instructions, or tomaintain periodic non-emergency communications. In some applications,signals may be fairly weak, such as at the fringe of a satellitefootprint, or from LEO (Low Earth Orbiting) satellite services such asIridium, Thuraya, Argos, Orbcomm, Inmarsat, GMDSS (Global MarineDistress Safety and Survival), Wavix, etc. In applications describedabove, weak signals, coupled with the insertion loss created by alengthy transmission line, and the limitations of the battery-poweredradio equipment, aggregate to make communications difficult.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 Block Diagram of an Embodiment

FIG. 2 Block Diagram of an Embodiment for UHF Satcom

FIG. 3A Power Supply

FIG. 3B RF System of an Embodiment

FIG. 3C E-Ink Display of an Embodiment

FIG. 4A Printed Circuit Boards, Top Layer (Copper) of an Embodiment

FIG. 4B Printed Circuit Board, Middle Layer 2 (Copper) of an Embodiment

FIG. 4C Printed Circuit Board, Bottom Layer (Copper) of an Embodiment

FIG. 4D Printed Circuit Board, Bottom Silk Screen Layer of an Embodiment

FIG. 4E Printed Circuit Board, Top Silk Screen Layer of an Embodiment

FIGS. 5A-H Physical Appearance of an Embodiment

FIG. 6 High-Level Method Flow Chart of Disclosed Embodiments

DETAILED DESCRIPTION OF THE INVENTION

The following description and drawings are illustrative and are not tobe construed as limiting. Numerous specific details are described toprovide a thorough understanding. However, in certain instances,well-known or conventional details are not described in order to avoidobscuring the description. References to “one embodiment” or “anembodiment” in the present disclosure are not necessarily references tothe same embodiment; and, such references mean at least one.

Reference in this specification to “one embodiment” or “an embodiment”or “a particular embodiment” means that a particular feature, structure,or characteristic described in connection with the embodiment isincluded in at least one embodiment of the disclosure. The appearancesof the phrase “in one embodiment” or substantially similar phrases invarious places in the specification are not necessarily all referring tothe same embodiment, nor are separate or alternative embodimentsmutually exclusive of other embodiments. Moreover, various features aredescribed which may be exhibited by some embodiments and not by others.Similarly, various requirements are described which may be requirementsfor some embodiments but not other embodiments.

FIG. 1 illustrates an embodiment of a radio frequency antenna systemapparatus comprising an Antenna 101. By way of example, but notlimitation, an Antenna 101 may be a Turnstile antenna (a pair ofconcentric, orthogonal or perpendicular dipole antennas) fed by aQuadrature Hybrid Coupler, or another passive or active antennastructure, such as a dipole antenna. Said Antenna 101 may incorporateelectrically tuning means to adjust its impedance matching, for example,for transmit or receive portions of the band.

An embodiment may comprise a Selective Power Separator 102, which may bea switch (capable of routing signals through two or more differentpaths, as determined by one or more control signals), a diplexer (whichcan route signals through two or more different paths, as determined bythe signal's carrier frequency), a directional device, such as acirculator, an isolator, a directional coupler, or any active circuitequivalent (which can route signals through two or more different paths,as determined by the direction of the signal's flow) now known in theart or later to be developed. In an embodiment, a transmit path may beeffectuated by means of a Transmission Line 103, such as, by way ofexample but not limitation, a coaxial cable. A Selective Power Separator102 may comprise one or a plurality of low loss, single pole, doublethrow (SPDT) switches, at least one for transmit signals and at leastone for receive signals, in which the transmit path is bypassed (e.g.,where a transmit path is effectuated by means of a Transmission Line103).

An embodiment may incorporate in its transmit path or receive path, orboth, a Radio Frequency Power Protection Input Device 104, such as alimiter (which may comprise a pin diode), the sensitivity of which maybe enhanced with the addition of a sensitive detector (which maycomprise a detector diode). Said Radio Frequency Power Protection InputDevice 104 may comprise a two-stage limiter, and to enhance sensitivityof the limiter, further may comprise a Schottky diode detector, whichmay provide effective signal limitation below +10 dBm, and may be under−10 dBm to safeguard an LNA. An embodiment further may include in itstransmit path or receive path, or both, a Low Noise Amplifier (LNA) 105,which may having a Low Noise Figure (LNF) under four dB.

An embodiment may comprise a Radio Frequency Power Protection OutputDevice 106, which may be similar to a Radio Frequency Power ProtectionInput Device 104, and may comprise a multi-stage limiter, and to enhancesensitivity of the limiter, further may comprise a Schottky diodedetector, which may provide more effective signal limitation. By way ofexample, but not limitation, with the addition of a Schottky diodedetector, a +10 dBm limiter could provide effective signal limitationunder −10 dBm to safeguard an LNA. A Selective Power Combiner 107, whichmay be similar to a Selective Power Separator 102, may be included in anembodiment.

In an embodiment, an Attenuator 108 may be included to stabilize theoperation of internal radio circuits, manage signal power levels, andassure a maximum impedance mismatch to keep a signal's Voltage StandingWave Ratio (VSWR) under a specified limit. An Attenuator 108 may have avalue under three dB. An embodiment may comprise a Radio FrequencyInterface 109, such as, by way of example and not limitation, a coaxialconnector, which may serve to connect an embodiment to a radiotransceiver (for two-way communications), or a radio receiver (forone-way communications).

A Controller Circuit 110, which may comprise sensors, actuators andsignal processing means, such as a microcontroller, a microprocessor,programmable logic (PAL/Programmable Array Logic, GAL/Generic ArrayLogic, CPLD/Complex Programmable Logic Device, FPGA/Field-ProgrammableGate Array, etc.), or a dedicated circuit made with discrete devices,may be incorporated in an embodiment to serve to manage various elementsin an embodiment. These elements may include, but are not necessarilylimited to, an Antenna 101, a Selective Power Separator 102, a RadioFrequency Power Protection Input Device 104, a Low Noise Amplifier (LNA)105, a Radio Frequency Power Protection Output Device 106, a SelectivePower Combiner 107, an Attenuator 108, and the Controller Circuit 110itself. A Controller Circuit 110 in an embodiment may comprise one ormore sensors for input and output radio signal levels, input and outputlimiter feedback, a transmit/receive detector, one or more batteries,one or more battery chargers, one or more LNA supply sensors, one ormore LNA bias sensors, one or more temperature sensors, or anycombination thereof. In an embodiment, a Controller Circuit 110 maycomprise actuators to connect and disconnect power or batteries, orboth, to control a Selective Power Separator 102 or a Selective PowerCombiner 107, or both, to tune an Antenna 101, to communicate withDisplay Means 111B and any signal processing means of the ControllerCircuit 110 itself.

An embodiment may include a User Interface 111, which may comprise InputMeans 111A, such as one or more push-button switches, a small keyboard,or other means of data input now known in the art or later to bedeveloped, and Display Means 111B, such as Electronic Paper (E-Ink), LCD(Liquid Crystal Display), LED (Light Emitting Diode), or other means ofdisplaying output now known in the art or later to be developed. Anembodiment may comprise Input Means 111A that are waterproof. In anembodiment, Display Means 111B may be waterproof. A Display Means 111Bmay comprise a Voltage Doubler 111C.

In an embodiment, one or more Battery Circuits 112 comprising batteries,which further may comprise temperature sensors and temperaturedelimiters or voltage sensors and voltage delimiters, or both, may beemployed to provide direct current (DC) power to the circuits of anAntenna 101, a Selective Power Separator 102, a Radio Frequency PowerProtection Input Device 104, a Low Noise Amplifier (LNA) 105, a RadioFrequency Power Protection Output Device 106, a Selective Power Combiner107, an Attenuator 108, a Radio Frequency Interface 109, and aController Circuit 110. Batteries in an embodiment may be rechargeablefor convenience, and an embodiment may comprise one or more BatteryChargers 113 to manage the replenishment of battery energy. DC power canbe supplied in an embodiment via a Radio Frequency Interface 109, orthrough a separate connection or connector, eliminating the need forbatteries. An embodiment may comprise one or more Energy-GeneratingMeans 114, such as one or more solar cells, a crank generator, or othermeans of generating energy, now known or later to be developed in theart, to produce energy when operating an embodiment in remote locations.In an embodiment, a Controller Circuit 110 may manage a User Interface111, one or more Battery Circuits 112, one or more Battery Chargers 113,one or more Energy-Generating Means 114, or any combination thereof.

An embodiment may comprise a Gravity Orientation Sensor 115 andPolarization Control Means 116 to enable inversion of polarization fromRight Hand Circular (RHC) to Left Hand Circular (LHC). Such anembodiment may function in both an upright and inverted position, forexample, if an embodiment is affixed upside-down to the roof of thecockpit of an aircraft.

An embodiment suitable for use in communications via UHF or VHFintra-team communication may comprise an Antenna 101 that is linearlypolarized, such as a dipole (electric dipole), a loop (often referred toas a magnetic dipole), or an unbalanced dipole-like structure enablingit to be human-wearable.

A block diagram of an embodiment suitable for use in communications viaUHF Satcom, such as military communications, is presented in FIG. 2. Byway of example and not limitation, the Antenna 101 in the embodimentpresented in FIG. 2 may be a Turnstile Antenna 201, comprising pair ofconcentric, orthogonal or perpendicular dipole antennas fed by aquadrature hybrid coupler, in which the elements may be tuned, toimprove efficiency at both transmit and receive frequencies. SchematicDiagrams for the construction of such an embodiment have been providedin FIGS. 3A-C, 4A-E, and 5-A-N for additional clarification.

In a half-duplex system, there are two clearly defined paths or channelsbetween communicating parties, but the communication is one direction ata time such that each party can communicate with the other, transmittingand receiving signals at different times, but not simultaneously. Anembodiment appropriate for communications via UHF Satcom may comprise ahalf-duplex system, which produces the lowest Antenna Noise Figure(ANF), and thus greater sensitivity. This is so because the insertionloss of a switch used as a Selective Power Separator 102 or of a switchused as a Selective Power Combiner 107 is typically between 0.2 and 1.0dB at UHF frequencies, whereas a diplexer's insertion loss rangesbetween two and six dB within the UHF Satcom spectrum. Furthermore, aswitch is physically much smaller than a diplexer at low UHFfrequencies. A circulator in this range would be both large and heavy,as it includes a permanent magnet. It also would interfere with the useof a compass. Active directional circuits would consume much more DCpower than a switch (which usually draws under 50 microAmperes ofcurrent), as it would need to have a wide dynamic range, capable ofsupporting UHF signal levels up to 25 watts, which is typical ofstandard military radios, such as a PRC-117 or PSC-5.

An embodiment may be capable of transmitting up to 25 watts, whileproviding a receive gain of approximately 20 dB, with an ANF ofapproximately 1.5 dB, and a total, peak DC power consumption of 4.5milliAmperes. A Battery Circuit 112 of an embodiment may compriseLithium-Ion batteries, Lithium Iron Phosphate (LiFePo4) batteries,Nickel Metal Hydride batteries, or other forms of batteries now known inthe art or later to be developed. Without the aid of one or more solarcells or other Energy-Generating Means 114, a Battery Circuit 112 of anembodiment comprising four AAA-size Lithium-Ion batteries or LithiumIron Phosphate (LiFePo4) batteries may run continuously forapproximately nine days on a four-hour charge. If one or more solarcells were used as an Energy-Generating Means 114 in an embodiment,battery life could be extended automatically when said one or more solarcells were to be exposed to sunlight during normal use. A ControllerCircuit 110 in an embodiment may be employed to manage battery use byturning off unused circuitry, while maintaining continuous displayupdates and user interaction, to extend battery life up to 52 days on asingle charge, with no solar cell contribution.

To accelerate and ensure a proper write to an E-Ink display in anembodiment, a Voltage Doubler 111C, may be enabled and used, but onlyduring a display update. E-Ink technology requires a potential of 5-15volts to write, but the batteries of a Battery Circuit 112 providingpower to an embodiment comprising an E-Ink as a Display Means 111B mayhave voltages below the minimum five volts. By way of example, and notlimitation, such batteries could be Li-Ion cells of 3.50-4.20 volts orLiFePo4 cells of 2.50-3.40 volts, for which a Voltage Doubler 111C couldproduce 7.0-8.4 volts or 5.0-6.8 volts, respectively.

In an embodiment, a Controller Circuit 110 may comprise amicrocontroller, such as Microchip's PIC18F26K20, to perform its morecomplex functions. This type of technology is sequential, requiring aclock that potentially generates radio interference. Such interferencemay be managed through adequate filtering of each pin of amicrocontroller, and by selecting a low clock frequency and creatingtime-efficient firmware. By way of example, but not limitation, acrystal clock frequency well below the UHF spectrum, such as 153.6 kHz,may be selected. To further reduce potential radio interference by aclock, a ferrite bead, tuned to the low UHF spectrum, may be placed inseries with a capacitor-loaded crystal. In an embodiment, a convenientchoice of clock frequency could be the Color Burst frequency of 3.57954MHz, which is popular in microcontroller applications. With adequatecircuit design, any clock frequency under 10 MHz may be usedsuccessfully in an embodiment.

An embodiment may comprise as its Display Means 111B a multi-segmentE-Ink display, by way of example and not limitation, Part NumberSC002221, to provide continuous information to a user, which may beupdated once every 10 seconds under full operation and once every 40-60seconds, so that overall current consumption of said Display Means 111Bmay be only a few microAmperes (possibly under 10 uA). E-Ink displaysonly consume energy when information is changed, so while informationdoes not change, they consume no energy.

In an embodiment, to handle a desired signal power level, e.g., 25watts, a Selective Power Separator 102 and Selective Power Combiner 107may be provided by a solid-state pair of tandem switches which, by wayof example, and not limitation, could be Silicon-On-Insulator Skyworkspart number SKY13374-397LF, which may rapidly switch between transmitand receive modes in less than 50 microseconds (measured at five uS).The discharge rate of the power protection stages (dual-stage limiterwith detector boost) may be set to 875 microseconds (0.85 ms) by a 1.0kiloOhm resistor in a detector boost circuit, so it may be compatiblewith Demand Assigned Multiple Access (DAMA), a standard Military TimeDivision Multiplex protocol that enables multiple users to communicatewithin a same channel. Adjusting a resistor value up or down from 1 kOhmmay allow the discharge rate to increase or decrease, respectively. DAMAspecifications allow for a 1.25 ms guard band between time blocks, so at0.85 ms, power protection is effected by keeping the input and output ofa Low Noise Amplifier 105 in high attenuation long after the SelectivePower Separator 102 and Selective Power Combiner 107 have settled intotheir proper state, receive or transmit. In an embodiment, a ControllerCircuit 110 may include a sensitive detector, a stable voltage referenceand a low power, fast comparator to sense and drive or actuate theSelective Power Separator 102 and Selective Power Combiner 107 in thepresence of transmitter signals (large signals exceeding the referencevoltage).

FIG. 3A presents one possible configuration of an RF system in anembodiment. FIG. 3B provides an example of one possible configuration ofa controller and display in an embodiment. FIG. 3C displays one possibleconfiguration for an E-Ink Display in an embodiment.

FIG. 4A depicts one possible configuration for the top layer of aprinted circuit board in an embodiment. FIG. 4B reflects one possibleconfiguration for a second middle layer of a printed circuit board in anembodiment. FIG. 4C illustrates one possible configuration for a bottomlayer of a printed circuit board in an embodiment. FIG. 4D presents onepossible configuration of a bottom layer—a silkscreen layer—for aprinted circuit board in an embodiment. FIG. 4E provides an example ofone possible configuration of a top layer—a silkscreen layer—for aprinted circuit board in an embodiment,

FIG. 5A is a view of the top of an embodiment reflecting a coaxial cablethat might serve as a Transmission Line 103 to be attached to a RadioFrequency Interface 109, and radiating elements of an Antenna 101, whichhappens to be a Turnstile antenna. FIG. 5B is a bottom view of anembodiment employing Mounting Means 502 to allow it to be secured. In anembodiment, such Mounting Means 502 may be a 20-thread mounting insertto accept a ¼-inch cylindrical threaded fastener, though many othersecure means of fastening well known in the art could be employed.

FIG. 5C presents an orthogonal view of an embodiment with its Antenna101, being a Turnstile antenna, showing its radiating elements andMounting Means 502 for the embodiment. In FIG. 5D, and RF PrintedCircuit Board for an embodiment is visible.

In FIG. 5E, the back of a printed circuit board for a Control Circuit109 in an embodiment is visible, as are four AAA battery cells embeddedin the back of the printed circuit board. FIG. 5F reveals an embodimentcomprising a user pushbutton as Input Means 111A, and an E-Ink displayas Display Means 111B, as well as a solar cell serving asEnergy-Generating Means 114.

FIG. 5G shows a Radio Frequency (RF) Electronics Board for anembodiment, a Hybrid Board and matching circuit, and shunt coils toprovide electrostatic discharge (ESD) grounding for the system. In FIG.5H, an RF Electronics Board is illustrated.

Embodiments disclosed herein include the capability of minimizing theunnecessary consumption of power by leaving an Antenna 101 powered off,i.e., in passive mode, so that only the signal processing means within aController Circuit 110, a Selective Power Separator 102 and a SelectivePower Combiner 107 remain on. Upon commencement of transmission by aradio operator, such as a dismounted warfighter, a signal processingmeans in a Controller Circuit 110, such as a microprocessor, may bealerted that an Antenna 101 needs to be powered on. Signal processingmeans of a Controller Circuit 110 then may issue a command to turn on anAntenna 101 for non-MUOS communications. Thus, upon mere initiation of atransmission by a radio operator, an Antenna 101 automatically may bepowered up for non-MUOS communications.

An Antenna 101 will remain powered on until a radio operator manuallyinputs a command or a sequence of commands to power it off. A firstmanual input command or sequence of commands can power off an Antenna101 upon entry of the first command or command sequence by a radiooperator. A second manual input command or sequence of commands cancause an LFA to remain powered on for a specific period of timedesignated by a radio operator upon entry of the second command orcommand sequence by a radio operator.

Communications via the latest MUOS satellite systems require that anAntenna 101 remain in passive mode. Thus, the automatic activation of anAntenna 101 upon the commencement of transmission may be overridden by athird manual input command, so that an Antenna 101 will remain inpassive mode, upon entry of the third command or command sequence by aradio operator. Once this MUOS communications mode has been activated bya radio operator, non-MUOS communications cannot take placenon-passively until the entry by a radio operator of a fourth manualinput command or sequence of commands that can cause an Antenna 101 topower up from its passive mode.

1. A method comprising the steps of: Placing an Antenna in a non-MUOSmode with the power off (passive state) using an input command orcommand sequence; Initiating a radio transmission and thereby alertingsignal processing means in a Controller Circuit that an Antenna needs tobe activated (powered on); Issuing a command to turn on an Antenna fornon-MUOS Communications by way of signal processing means of aController Circuit, thereby causing an Antenna to activate (power on)from a passive (power off) state.